The present invention relates to a filter arrangement with an upright filter having a filter housing and filter insert for cleaning lubricating oil of an internal combustion engine in which the filter is fastened at a filter socket located in the lower part in the installed condition of the filter arrangement, and in which a first channel is provided in the socket for the feed of lubricating oil, a second channel is provided for the discharge of clean oil and a third channel is provided for the discharge of oil out of the interior of the filter, and in which a passage is forcibly opened during the change of the filter insert which leads from the inside of the filter housing to the third channel.
Such a filter arrangement is disclosed in the DE-PS No. 25 55 420. The disadvantage exists with this prior art filter arrangement that during a filter change, dirty oil reaches the clean oil channel. Additionally, this prior art filter arrangement is structurally very high by reason of the necessity to arrange the individual channels in the filter socket one above the other.
The present invention is concerned with the task to so construct the filter arrangement of the aforementioned type that during the filter change a necessary emptying of the interior of the filter is attained in a simple manner without mixing clean oil with dirty oil and accompanied with a low structural height of the entire filter arrangement.
The underlying problems are solved according to the present invention in that the passage is arranged in a collar of the filter socket narrowly surrounding the lower part of the filter housing and is sealingly covered off by the filter housing in the installed position thereof.
In the filter arrangement according to the present invention, the passage is necessarily controlled by the filter housing into its open position when the filter is lifted up so that the oil can flow out of the filter interior into the third channel and through the latter into an oil reservoir such as the oil pan of the internal combustion engine. This third channel is laid out completely independent of the two other oil-conducting channels so that a mixing of clean oil and dirty oil is precluded. Additionally, it is arranged approximately at the height of the lower area of the filter housing and not below the two other channels so that the entire structural height of the filter arrangement according to the present invention is reduced compared to the prior art type of filter arrangement. The present invention is utilizable both with a separate construction of the filter insert and filter housing as also with a construction of filter insert and filter housing in a structural unit as so-called throw-away cartridge.
A filter arrangement is additionally disclosed in the DE-OS No. 33 44 568 in which the mixing of clean oil and dirty oil is avoided when changing the filter. However, the arrangement of a special valve is necessary for that purpose; additionally, the arrangement of the channels one above the other results in a considerable structural height.
According to another feature of the present invention, the construction of the filter arrangement assures already during the loosening of the filter the opening of the passage and therewith the emptying of the filter housing without the need for the person carrying out the filter change operation to pay particular attention thereto. This is achieved by a prestressed spring engaging at the filter housing or at the filter insert which during loosening the fastening of the filter lifts the same from the filter socket up to the full opening of the passage.
According to still another feature of the present invention, the filter arrangement assures the sealing of the interior of the filter with respect to the outside by a single seal, and more particularly both during the operation as also during the emptying of the filter interior. This is achieved in that an annular seal is arranged between the filter housing and the collar above the passage which remains effective during the lifting of the filter housing up to the full opening of the passage.